In general, the present invention relates to the field of communication systems, more particularly, to a communication device that transmits a communication signal during repetitive time slots.
Communication systems that communicate voice and data messages are extensively used in telephony and wireless communication systems. For example, ETSI (European Telecommunication Standard Institute) has specified a GSM (Global Standard for Mobile Communication) protocol that uses TDMA (time division multiple access) to communicate control, voice and data information over RF (radio frequency) channels. In the U.S., the TIA (Telecommunication Industry Association) has published a number of Interim Standards, such as IS-136, that define various versions of D-AMPS (Digital Advanced Mobile Phone Service) with the capability of transmitting voice and data to subscribers. GPRS (General Packet Radio Service) is a non-voice value added service that allows information to be sent and received across GSM as well as the IS-136 systems. GPRS supplements today""s Circuit Switched Data and SMS (Short Message Service) of the GSM at theoretical maximum speeds of up to 171.2 kilobits per second (kbps) using eight timeslots at the same time. Because of the spectrum efficiency of GPRS, there is less need to build in idle capacity that is only used in peak hours. GPRS therefore lets network operators maximize the use of their network resources in a dynamic and flexible way, along with user access to resources and revenues.
GPRS involves overlaying a packet based air interface on the existing circuit switched GSM network, thereby giving end users an option to use a packet-based data service. With GPRS, the information is split into separate but related xe2x80x9cpacketsxe2x80x9d for transmission and re-assembly at a receiving end. Because of packet switching configuration of GPRS, radio resources are used only when end users are actually sending or receiving data. Rather than dedicating a radio channel to an end user communication device for a fixed period of time, the available radio resource can be concurrently shared between several communication devices, thereby allowing a large number of GPRS users to share the same bandwidth within a single cell. The actual number of users supported depends on the application being used and how much data is being transferred.
High immediacy is a very important feature for time critical applications. Subject to radio coverage, GPRS also facilitates instant connections whereby information can be sent or received immediately as the need arises. GPRS also facilitates new applications not previously available over GSM networks due to the limitations in speed of Circuit Switched Data (9.6 kbps) and length of the SMS (Short Message Service) which is 160 characters. For example, GPRS enables Mobile Internet functionality by allowing inter-working between the existing Internet and a GPRS-enabled network. As such, any service that is used over the fixed Internet today, for example, FTP (File Transfer Protocol), web browsing, chat, email, telnet, can also be available over the GPRS-enabled network.
It is known that communication signals that are communicated over wireless channels are influenced when in proximity of an object or human body. When a communication device transmits electromagnetic radiation in proximity of the object, the electromagnetic radiation can be perturbed and suppressed in the direction of the object. The influence of the object on the electromagnetic radiation can effect communication performance of the communication device. For example, packet data transmissions in systems that provide GPRS can be degraded when a GPRS enabled communication device is in the proximity of an object.
Accordingly, there exists a need to improve communication performance when a communication device is in proximity of an object.